Horton

Re: [PoC] Improve dead tuple storage for lazy vacuum

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: John Naylor <john.naylor@enterprisedb.com>
Cc: Andres Freund <andres@anarazel.de>, Nathan Bossart <nathandbossart@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, Yura Sokolov <y.sokolov@postgrespro.ru>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2022-12-01T08:02:57Z
Lists: pgsql-hackers 
On Thu, Dec 1, 2022 at 4:00 PM John Naylor <john.naylor@enterprisedb.com> wrote:
>
>
> On Wed, Nov 30, 2022 at 11:09 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> >
> > I've investigated this issue and have a question about using atomic
> > variables on palloc'ed memory. In non-parallel vacuum cases,
> > radix_tree_control is allocated via aset.c. IIUC in 32-bit machines,
> > the memory allocated by aset.c is 4-bytes aligned so these atomic
> > variables are not always 8-bytes aligned. Is there any way to enforce
> > 8-bytes aligned memory allocations in 32-bit machines?
>
> The bigger question in my mind is: Why is there an atomic variable in backend-local memory?

Because I use the same radix_tree and radix_tree_control structs for
non-parallel and parallel vacuum. Therefore, radix_tree_control is
allocated in DSM for parallel-vacuum cases or in backend-local memory
for non-parallel vacuum cases.

Regards,

-- 
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com

Commits

  1. radixtree: Fix SIGSEGV at update of embeddable value to non-embeddable.

  2. Get rid of anonymous struct

  3. Teach radix tree to embed values at runtime

  4. Teach TID store to skip bitmap for small numbers of offsets

  5. Use bump context for TID bitmaps stored by vacuum

  6. Fix alignment of stack variable

  7. Use TidStore for dead tuple TIDs storage during lazy vacuum.

  8. Rethink create and attach APIs of shared TidStore.

  9. Fix inconsistent function prototypes with function definitions.

  10. Fix a calculation in TidStoreCreate().

  11. Fix potential integer handling issue in radixtree.h.

  12. Add TIDStore, to store sets of TIDs (ItemPointerData) efficiently.

  13. Fix link error for test_radixtree module on Windows

  14. Blind attempt to fix ODR violations

  15. Fix incorrect format specifier for int64

  16. Fix redefinition of typedefs

  17. Add template for adaptive radix tree

  18. Fix signedness error in 9f225e992 for gcc

  19. Introduce helper SIMD functions for small byte arrays

  20. Optimize vacuuming of relations with no indexes.

  21. Add bound check before bsearch() for performance

  22. Allocate consecutive blocks during parallel seqscans